Oil-based ink composition for ballpoint pen using oil-based ink

ABSTRACT

In order to provide an ink composition for a ballpoint pen which suppresses blobbing of a written letter at the start of writing and is capable of being excellent in a soft smooth feeling on writing and an oil-based ballpoint pen using the ink composition, there is provided an oil-based ink composition for a ballpoint pen, involving at least a coloring material, a resin and a solvent selected from the group consisting of an alcohol, a polyhydric alcohol and a glycol ether each having a vapor pressure of 0.001 mmHg or more at 25° C. as a main solvent which occupies 50% or more of an entire solvent and, further, satisfying at least one of the following (a) to (c): (a) further involving a phosphoric acid ester neutralized material and polypropylene glycol; 
 
(b) further involving a chemical substance represented by the following chemical structure (1) or (2):  
                 
 
in which R represents an alkyl group having from 10 to 30 carbon atoms; or  
                 
in which R represents an alkyl group having from 10 to 30 carbon atoms; and (c) while allowing that the solvent selected as the main solvent from the group consisting of an alcohol, a polyhydric alcohol and a glycol ether each having no aromatic ring in a molecular structure occupies 50% by weight or more of an entire solvent, further involving a phosphoric acid ester neutralized mixture, still further involving an additional solvent selected from the group consisting of an alcohol, a polyhydric alcohol and a glycol ether each having an aromatic ring in an amount, based on an entire weight of the ink composition, of from 0.1 to 15% by weight.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an oil-based ink composition for aballpoint pen which is suitably used as an oil-based ink for theballpoint pen and is excellent in suppressing blobbing of writtenletters at the start of writing, provides a soft smooth feeling ofwriting and, further, allows the ink to be quickly transferred.

BACKGROUND ART

Heretofore, in an oil-based ballpoint pen, a drawback is liable to occurin which, when a solvent of an ink at a tip end portion of a ball tip isevaporated and, then, the ink becomes thickened, the ink is not easilyejected at the start of writing to cause blobbing of written letters, ora written letter with a sufficient density cannot be obtained until theball starts fully rotating. Further, this blobbing phenomenon greatlydepends on environmental conditions and often occurs underlow-temperature or high-temperature conditions to cause distress. Stillfurther, in a case of using a solvent having a high volatility, asdefined in the Claims, this phenomenon occurs outstandingly and becomesa serious problem. In order to solve these problems, various effortshave heretofore been exerted. For example, in an invention according toJapanese Examined Patent Publication (Kokoku) No. 61-52872, theinvention in which fluidity of an ink is maintained by adding a specificnonionic surfactant is described; in Japanese Examined PatentPublication (Kokoku) No. 57-38629, an invention of using a high boilingpoint aromatic hydrocarbon as a solvent for suppressing deterioration ofan ink to be caused by drying or by absorbing moisture is described; inan invention according to Japanese Unexamined Patent Publication (Kokai)No. 3-28279, fluidity of an ink is maintained by adding a phosphoricacid ester; in an invention according to Japanese Unexamined PatentPublication (Kokai) No. 6-247093, an ink is prevented from beingcompletely dried out by using a nonvolatile solvent.

In an invention according to Japanese Unexamined Patent Publication(Kokai) No. 11-158421, by compounding a salt of a basic dye with aphosphoric acid ester, crystallization of a dye at a pen tip issuppressed and the ink is allowed to be in a state of from a grease to apaste such that the ink is hard to dry-solidify at a tip end portion ofa pen, whereby the fluidity of an ink is maintained and, as a result,smooth writing at the start of writing is secured, to thereby improvethe problematic blobbing phenomenon. Also, in an invention according toJapanese Unexamined Patent Publication (Kokai) No. 11-21495, the sameeffect as described above is generated by neutralizing an acidicpolyoxyethylene alkyl ether phosphoric acid ester with a predeterminedalkyl alkanolamine or morpholine. However, the amine substance used onthis occasion has a strong odor and high reactivity and, therefore, adegree of freedom of selection of solvents, dyes and the like is narrow.Further, there is no measure for determining a stable neutralizedmaterial.

However, although there scarcely arises a problem in a solvent havingsuch a vapor pressure of less than 0.01 mmHg as used in a conventionaloil-based ballpoint pen, in the case of using a solvent having a highvapor pressure, when an ink agglomerate is solidified in a periphery ofa ball, an extremely high writing load is required to start writing inwhich the ball moves.

An object of the present invention is to provide an oil-based inkcomposition for a ballpoint pen which, unlike conventional techniques,suppresses blobbing of a written letter at the start of writing and isexcellent in soft smooth writing at the start of writing, and aballpoint pen using the ink composition.

DISCLOSURE OF THE INVENTION

In order to attain the aforementioned object, it has been found that theabove-described problems can be solved by giving an oil-based inkcomposition, for a ballpoint pen according to the present invention, thecharacteristics as described below, to thereby accomplish the presentinvention.

[1] An oil-based ink composition for a ballpoint pen, comprising atleast a coloring material, a resin and a solvent selected from the groupconsisting of an alcohol, a polyhydric alcohol and a glycol ether eachhaving a vapor pressure of 0.001 mmHg or more at 25° C. as a mainsolvent which occupies 50% or more of an entire solvent and, further,satisfying at least one of the following (a) to (c):

(a) further comprising a phosphoric acid ester neutralized material andpolypropylene glycol;

(b) further comprising a chemical substance represented by the followingchemical structure (1) or (2):

in which R represents an alkyl group having from 10 to 30 carbon atomsor

in which R represents an alkyl group having from 10 to 30 carbon atoms;and

(c) comprising a solvent selected as the main solvent from the groupconsisting of an alcohol, a polyhydric alcohol and a glycol ether eachhaving no aromatic ring in a molecular structure in an amount of 50% byweight or more of an entire solvent, further comprising a phosphoricacid ester neutralized mixture and, still further comprising anadditional solvent selected from the group consisting of an alcohol, apolyhydric alcohol and a glycol ether each having an aromatic ring in anamount, based on an entire weight of the ink composition, of from 0.1 to15% by weight.

[2] The oil-based ink composition for the ballpoint pen according to theabove-described [1], in which the glycol ether is a solvent representedby the following chemical structure (3):

in which R¹, R² and R³ each independently represent H or CH₃.

[3] The oil-based ink composition for the ballpoint pen according to theabove-described [2] or [2], in which the glycol ether is at least onetype selected from the group consisting of: propylene glycol monomethylether, 1,3-butanediol, 3-methoxy-1-butanol and3-methyl-3-methoxy-1-butanol.

[4] The oil-based ink composition for the ballpoint pen according to theabove-described [1] to [3], wherein the main solvent is contained in anamount, based on an entire solvent, of 60% by weight or more.

[5] The oil-based ink composition for the ballpoint pen according to theabove-described [1] to [4], wherein the main solvent is contained in anamount, based on an entire solvent, of 70% by weight or more.

[6] The oil-based ink composition for the ballpoint pen according to anyone of the above-described [1] to [5], wherein the phosphoric acid esterneutralized material is contained in an amount, based on an entireweight of the ink composition, of from 0.01 to 15% by weight.

[7] The oil-based ink composition for the ballpoint pen according to theabove-described [1] to [6], in which polypropylene glycol has amolecular weight of 1,000 or more and is added in an amount of 0.01% byweight to 10% by weight.

[8] The oil-based ink composition for the ballpoint pen according to theabove described [1] to [7], in which the coloring material is a pigment,or a pigment and a dye in combination.

[9] The oil-based ink composition for the ballpoint pen according to theabove-described [1] to [8], in which an amount of the chemical substancerepresented by the chemical structure (1) or (2) to be added is, basedon the ink composition, from 0.5% by weight to 10% by weight.

[10] The oil-based ink composition for the ballpoint pen according tothe above-described [9], further comprising a mixture of a phosphoricacid ester and an amine-type compound.

[11] An oil-based ballpoint pen, containing the oil-based inkcomposition according to the above-described [1] to [10] in a refill.

[12] The oil-based ballpoint pen according to the above-described [11],further containing an ink follower in a rear of the ink.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional diagram schematically showing a refill of anoil-based ballpoint pen. In FIG. 1, a ballpoint pen tip 1 made of metalis connected with one end portion of an ink holding tube 2 made of atransparent plastic in a liquid-tight manner. Although the type ofstructure of the tip 1 varies depending on the occasion, a ball made ofmetal or ceramic is present at a tip end thereof, an ink 3 in an inkholding tube 2 passes through an inside of the tip 1 and is, then,subjected to writing by a ball at the tip end. A follower 4 is mountedin a rear of the ink 3 in the ink holding tube 2 and, as the ink 3 isreduced, the follower 4 follows the movement of a rear end portion ofthe ink 3. Such a refill as described above is contained in an outershaft, to thereby prepare a ballpoint pen.

MODE FOR CARRYING OUT THE INVENTION

<Solvent>

As is apparent from the description of solvents to be made below, anoil-based ballpoint pen according to the present invention moreaccurately means as a non-aqueous ballpoint pen; however, as this typeof pen is customarily called also as the oil-based ballpoint pen in theindustry, it is called so in the present invention.

As for a main solvent (50% by weight or more of the entire solvent) tobe used in a composition according to the present invention, a solventselected from among an alcohol, a polyhydric alcohol and a glycol ethereach having a vapor pressure of 0.001 mmHg or more at 25° C. is used. Byusing a specific solvent having such a high vapor pressure as describedabove, it becomes possible to provide the oil-based ballpoint pen whichgives a smooth written letter and an excellent feeling on writing. Anoil-based ink composition for a ballpoint pen according to the presentinvention has been developed to solve the problems unique to the casewhere a specific solvent having such a high vapor pressure as describedabove is used. The term “main solvent” as used herein is denoted as asolvent which is contained in an amount of 50% by weight or more of anentire solvent and may optionally be contained in an amount of 70% byweight or more or, further, 80% by weight or more or, particularly, 90%by weight or more.

Specific examples of the alcohols include aliphatic alcohols having 2 ormore carbon atoms, such as ethanol, n-propanol, isopropanol, n-butanol,isobutanol, tert-butyl alcohol, 1-pentanol, isoamyl alcohol, sec-amylalcohol, 3-pentanol, tert-amyl alcohol, n-hexanol, methyl amyl alcohol,2-ethyl butanol, n-heptanol, 2-heptanol, 3-heptanol, n-octanol,2-octanol, 2-ethyl hexanol, 3,5,5-trimethyl hexanol, nonanol, n-decanol,undecanol, n-decanol, trimethylnonyl-alcohol, tetradecanol,heptadecanol, cyclohexanol, 2-methyl cyclohexanol, benzyl alcohol andother various types of higher alcohols than described above.

Also, specific examples of the polyhydric alcohols include polyhydricalcohols having 2 or more carbon atoms and 2 or more hydroxyl groupswithin the molecule, such as ethylene glycol, diethylene glycol,3-methyl-1,3-butanediol, triethylene glycol, dipropylene glycol,1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexylene glycol andoctylene glycol.

Specific examples of the glycol ethers include methyl isopropyl ether,ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether,butyl ether, hexyl ether, 2-ethyl hexyl ether, ethylene glycol monohexylether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, diethylene glycol monobutylether, triethylene glycol monobutyl ether, tetraethylene glycolmonobutyl ether, 3-methyl-3-methoxy-1-butanol, 3-methoxy-1-butanol,propylene glycol monomethyl ether, propylene glycol monoethyl ether,propylene glycol monopropyl ether, propylene glycol monobutyl ether,propylene glycol phenyl ether, propylene glycol tertiary butyl ether,dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether,dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether,tripropylene glycol monomethyl ether, tripropylene glycol monobutylether and tetrapropylene glycol monobutyl ether.

As for particularly preferable solvents, the solvents represented by thechemical structure (3) such as propylene glycol monomethyl ether,1,3-butanediol, 3-methoxy-1-butanol and 3-methyl-3-methoxy-1-butanol arementioned.

Among the solvent described above, particularly preferred are glycolethers having from 2 to 7 carbon atoms because of their conspicuouseffects. In view of safety, oral toxicity or the like, an organicsolvent other than ethylene glycol derivatives is preferably used.

In addition to the above described solvents, a solvent shown below canalso be added within the range of not hindering solubility of a mixturewith a phosphoric acid ester and an amine-type compound or volatility.

Examples of such solvents include derivatives of polyhydric alcoholsand, further, derivatives of a sorbitan fatty acid type, a polyglycerinhigher fatty acid type, a sucrose fatty acid type and a propylene glycolfatty acid type.

As for solvents of esters, various types of esters such as propyleneglycol methyl ether acetate, propylene glycol diacetate,3-methyl-3-methoxybutyl acetate, propylene glycol ethyl ether acetate,ethylene glycol ethyl ether acetate, butyl formate, isobutyl formate,isoamyl formate, propyl acetate, butyl acetate, isopropyl acetate,isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate,propyl propionate, isobutyl propionate, isoamyl propionate, methylbutyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethylisobutyrate, propyl isobutyrate, methyl valerate, ethyl valerate, propylvalerate, methyl isovalerate, ethyl isovalerate, propyl isovalerate,methyl trimethylacetate, ethyl trimethylacetate, propyltrimethylacetate, methyl caproate, ethyl caproate, propyl caproate,methyl caprylate, ethyl caprylate, propyl caprylate, methyl laurate,ethyl laurate, methyl oleate, ethyl oleate, caprylic acid triglyceride,tributyl citric acetate, octyl oxystearate, propylene glycolmonoricinolate, methyl 2-hydroxyisobutyrate and 3-methoxybutyl acetateare mentioned,

Specific examples of diethers or diesters each as a solvent having nohydroxyl group within the molecule include ethylene glycol diethylether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, diethylene glycol dimethyl ether anddipropylene glycol dimethyl ether.

<Coloring Material>

A coloring agent (coloring material) to be used in the oil-based ink forthe ballpoint pen according to the present invention is not particularlylimited and it is preferable to use a pigment or simultaneously use apigment and a dye in combinations. By using the pigment, excellentfastness can be realized. As for such pigments, carbon black, organicpigments of a phthalocyanine type, azo types including insoluble azotypes such as a monoazo, a disazo, a condensed azo and a chelate azo,soluble azo types such as a hard soluble azo and a soluble azo, aquinacridone type, a diketopyrrolopyrrole type, a threne type, adioxazine type, and an isoindolinone type and the like can be used.

Particularly, as for carbon black, a carbon black having a specificsurface area as small as possible is must be used and, on this occasion,that having a specific surface area of 100 m²/g or less as a valuemeasured by the BET method is preferred. Specifically, there are #33,#32, #30, #25, CF9 and the like of carbon black manufactured byMitsubishi Chemical Co., Ltd.; REGAL (400R, 500R, 330R, and 300R),ELFTEX (8, and 12), STERLING R and the like of carbon black manufacturedby Cabot Co., Ltd.; Printex (45, 40, 300, 30, 3, 35, 25, 200, A, and G),SB (250, and 200) and the like as being manufactured by Degussa AG.; andRAVEN (1040, 1035, 1020, 1000, 890, 890H, 850, 500, 450, 420, 410, H20,22, 16, and 14) and the like as being manufactured by ColumbianChemicals Co.

Further, as for the pigments, a pigment which is hard to dissolve in anorganic solvent and having an average particle diameter after dispersionof from 30 nm to 700 nm is preferred. An amount of the pigment to becompounded may be, based on the entire weight of the ink composition, inthe range of from 0.5 to 25% by weight, preferably from 0.5 to 20% byweight. The pigment can be compounded in the above-described ranges inaccordance with requirements.

The pigments which can be used in the present invention may be used eachindividually or in combinations of two or more thereof. If desired, adispersion using an inorganic pigment, or a dye, or others may also beadded within the range of not adversely affecting the dispersionstability. By using a dye, an excellent effect of color formation can beimparted. Further, other examples include resin emulsions obtained bypolymerizing styrene, acrylic acid, an acrylic acid ester, methacrylicacid, a methacrylic acid ester, acrylonitrile or an olefin-base monomer;emulsions of hollow resins which swell in the ink to become amorphous;and organic multicolor pigments comprising dyed resin particles obtainedby dyeing the above-described emulsion itself with a coloring material.

In a case in which the coloring material used in the present inventionis a pigment, conventionally known various types of methods can be usedto produce a pigment-dispersed ink composition. For example, respectivecomponents described above are compounded and stirred by a stirrer suchas dissolver, or mixed and pulverized by a ball mill, a roll mill, abead mill, a sand mill, a pin mill or the like and, then, the resultantmixture is centrifuged or filtered to remove coarse pigment particles,undissolved materials and mingled solids, to thereby easily prepare thepigment-dispersed ink composition.

The dyes as being used together with the pigments are not particularlylimited and can be used so long as they do not destroy a dispersionsystem. As for dyes, any dye selected from among dyes used in normal dyeink compositions, such as a direct dye, an acid dye, a basic dye, amordant/acidic mordant dye, a spirit-soluble dye, an azoic dye, asulfur/sulfur vat dye, a vat dye, a dispersion dye, an oil-soluble dye,a food dye and a metal complex dye, and an inorganic pigment and anorganic pigment used in normal pigment ink compositions can be used. Anamount of the coloring material to be compounded may be, based on theentire amount of the composition, from 1 to 50% by weight.

<Resin>

A resin is used in the oil-based ink composition of the ballpoint penaccording to the present invention. The resin for use in the oil-basedink composition for the ballpoint pen is added for the purpose of aviscosity adjustment or an abrasion improvement at a tip of the pen.When the pigment is contained, the resin is also used as a dispersingagent for the pigment. Examples of such resins include resinsrepresented by a ketone resin, a styrene resin, a styrene-acrylic resin,a terpene phenol resin, a rosin-modified maleic acid resin, a rosinphenol resin, an alkylphenol resin, a phenol type resin, a styrenemaleic acid resin, a rosin type resin, an acrylic resin, a urea aldehydetype resin, a maleic acid type resin, a cyclohexanone type resin,polyvinyl butyral and polyvinyl pyrrolidone.

An amount of any one of these resins to be compounded is preferably from1 to 30% by weight, more preferably from 1 to 20%. When the amount to becompounded is less than 1%, there arises difficulty in the viscosityadjustment or the abrasion at the tip of the pen, while, when it exceeds30% by weight, other starting materials than the resin may not becompounded or the feeling on writing is sometimes adversely affected.

In a case in which the pigment is used as the coloring material in theink composition as a preferred embodiment according to the presentinvention, a resin capable of dispersing the pigment may be selectedfrom among the above-described resins and used as the dispersant. Thedispersant is not limited on the kind thereof and any one may be used,irrespective of activator or oligomer, insofar as it can satisfy thepurpose. Specific examples of such dispersants include synthetic resinssuch as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral,polyvinyl ether, a styrene-maleic acid copolymer, a ketone resin,hydroxyethyl cellulose and derivatives thereof, and a styrene-acrylicacid copolymer, PO/EO adducts, and amine type oligomers of polyester.

EMBODIMENT (a)

One embodiment (a) of the present invention is characterized by furthercomprising a phosphoric acid ester neutralized material andpolypropylene glycol.

In this embodiment (a) of the present invention, the phosphoric acidester neutralized material exerts an effect of facilitating removal ofan ink agglomerate on a surface of a ball, to thereby exert an effect ofsuppressing a blobbing of a written letter at the start of writing, andexerts an effect of not only suppressing the blobbing of the writtenletter at the start of writing for a short period of time or a longperiod of time in cooperation with polypropylene glycol but alsoallowing an ink transfer at the time of writing at a low speed to besmoothly carried out.

The phosphoric acid ester to be used ordinarily comprises a phosphoricacid monoester, a diester and a trace amount of a triester. The esterstructure thereof is mainly a surfactant structure, including anaromatic group type or an aliphatic group type. In regard to an alkylgroup capable of forming a phosphoric acid ester structure, an alkylgroup obtainable from a natural or synthetic higher alcohol or the likeis introduced. Phosphoric acid esters having an alkyl group having from10 to 20 carbon atoms and a chain having from 0 to 50 polyoxyethylenemay be used. Particularly, a phosphoric acid ester having from 15 to 20carbon atoms and a chain having from 0 to 4 polyoxyethylene isfavorable.

Further, the phosphoric acid ester is used as a neutralized materialand, on this occasion, it is desirable to neutralize the phosphoric acidester with an amine type substance, particularly, an alkanol amine,polyoxyethylene alkylamine, an ampholytic surfactant, an aliphatic aminetype substance or the like. Particularly, as for these amine typesubstances, a tertiary amine is favorably used. Further, as for thealkanol amine, such alkanol amine as having a vapor pressure of 1 mmHgor less at 20° C. is favorable. Specifically, N-methyl diethylethanolamine, N,N-dibutyl ethanolamine, N-n-butyl diethanolamine,N-t-butyl diethanolamine, N,N-diethyl isopropanolamine, triethanolamineand the like are mentioned.

An amount of any one of these amines to be added is, based on an entireink composition, in the range of preferably from 0.01% by weight to 15%by weight, more preferably from 0.1 to 10% by weight and, particularlypreferably, from 0.1 to 8% by weight in terms of a neutralized mixture.When it is less than 0.01% by weight, the effect of easily removing theagglomerate on the surface of the ball is reduced, while, when itexceeds 15% by weight, it may sometimes become easy to generate aproblem in the quality of a drawn line in which the ink composition istoo easily repelled from the ball to break the drawn line.

The ink composition for the oil-based ballpoint pen according to thisembodiment (a) further comprises polypropylene glycol. The ink for theoil-based ballpoint pen which tends to be dry-solidified forms a film ofthe ink on the ball, for example, a metallic ball and such problem asdescribed above is particularly conspicuous in a case of containing thepigment; however, when polypropylene glycol is added, as the film of theink becomes hard to form, there is an effect of causing less blobbing atthe start of writing. Such phenomenon as described above helps not onlyto suppress the blobbing by repelling of the ink against the metallicball but it is also hard to form the ink film and, accordingly, it ispossible to suppress the blobbing even in such a short period of time asfrom 1 to 20 minutes.

A molecular weight of the polypropylene glycol is preferably as large aspossible because an amount thereof to be added can be small, to therebyenhance a drying property of the written line. The molecular weight (ona calculation basis) thereof is preferably 1000 or more, more preferably2000 or more and, still more preferably, 4000 or more.

An amount of polypropylene glycol to be added is preferably from 0.01 to10% by weight and, particularly preferably, 0.1 to 10% by weight. As theink using the pigment which tends to be dry-solidified becomes hard toform a film on the metallic ball in the above-described ranges, theeffect of less causing the blobbing at the start of writing is large.

When the amount to be added is less than 0.1% by weight which out of theabove-described range, the above-described effect is poor and, then, theball may sometimes stop rotating, while, when the amount exceeds 10% byweight, although depending on the raw material to be used, an amount ofa nonvolatile component becomes high and, then, it may sometimes occurthat a drying property of the written line is deteriorated or astrike-through thereof appears.

According to the embodiment (a) of the present invention, and differentfrom a prior method, an ink composition for the ballpoint pen, in whichthe blobbing of the written letter at the start of writing for a shortperiod of time or a long period of time is suppressed, to thereby enablean excellent soft smooth feeling on writing, is provided.

According to the embodiment (a) of the present invention, the reason forexerting such effects as described above is in the characteristics ofthe ink composition, namely, the ink having the pigment and volatilitygenerates the ink agglomerate on the metallic ball. However, althoughpolypropylene glycol to be used in this embodiment, particular thathaving a molecular weight of 1000 or more, acts against a pigmentdispersion in a poor solvent manner, since it has capability ofdissolving a resin or an affinity with the resin, it becomes difficultto form a hard ink agglomerate on the metallic ball. Accordingly, theblobbing or the like in the short period of time can be improved morethan ever. Further, as polypropylene glycol having a molecular weight of1000 or more becomes low in hydrogen bonding, the affinity to waterbecomes lower compared with that having a low molecular weight. Fromthis fact, it gives little adverse effect (increase in hygroscopicity)to the hygroscopic main solvent within the scope of claims. Under thesecircumstances, it becomes possible to provide the oil-based inkcomposition for the ballpoint pen in which the blobbing at the start ofwriting is improved, to thereby provide excellent soft smooth feeling ofwriting.

EMBODIMENT (b)

Another embodiment (b) of the present invention is characterized bycomprising a chemical substance represented by the following chemicalstructure (1) or (2):

wherein R represents an alkyl group having from 10 to 30 carbon atoms;or

wherein R represents an alkyl group having from 10 to 30 carbon atoms.

The chemical substance represented by the chemical structure (1) or (2)suppresses an increase of resistance, which is caused by components ofan ink, in a contact portion between a ball and a ball seat in a chipand prevents hindrance of rotation of the ball, to thereby exert aneffect of allowing the ink to be favorably transferred. Although thiseffect is unclear, it is conceivable that such an effect as lubricationis exerted by an interaction with ink raw materials, to the contactportion between the ball and the seat in the chip which hinders acontinuous laminar ink injection, or a coating effect by these materialsexhibits an action of such suppression as described above. Sinceabrasion is high, particularly in a case of the ink containing a pigmentas a coloring material, this effect is remarkable and useful. The alkylgroup in the chemical structure (1) or (2) preferably has from 10 to 30carbon atoms. Particularly preferably, the alkyl group in the chemicalstructure (1) has from 10 to 20 carbon atoms and still more preferablyhas from 12 to 18 carbon atoms. Specifically, those chemical substancesin a lauryl or stearyl form are put on the market; for example, ADEKAAMHOTE PB-30L (trade name) manufactured by ADEKA Co., Ltd., AMHITOL 86B(trade name) manufactured by Kao Corp., AM-301 (trade name) manufacturedby Nikko Chemicals Co., Ltd., and BISTA-ML, -MS, etc. (trade name)manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. are available in themarket. Further, the same holds true with the alkyl group in thechemical structure (2); for example, AM-3130N (trade name) manufacturedby Nikko Chemicals Co., Ltd., and BISTA-CAP (trade name) manufactured byMatsumoto Yushi-Seiyaku Co., Ltd. are available in the market.

An amount of the chemical substance represented by the chemicalstructure (1) or (2) to be added is, based on the ink composition,favorable in the range of from 0.5% by weight to 10% by weight. In theaforementioned range, even in the ink in which the pigment is used, aneffect of favorably transferring the ink without hindering the rotationof the metallic ball is remarkable. When such addition amount exceeds10% by weight, there is a fear of causing a problem in solubility or aproblem in stability in a humid condition from the standpoint of thehygroscopic property and, accordingly, the addition amount is favorablein the range of from 0.5% by weight to 10% by weight. It is moredesirable to reduce the addition amount as much as possible and, on thisaccount, it is more favorably from 0.5 to 10% by weight and, still morefavorably from 0.5 to 7.0% by weight.

In the embodiment (b), it is preferable to further use a mixture of thephosphoric acid ester and an amine-type compound. It is particularlypreferable to use as a neutralized material between the phosphoric acidester and the amine-type compound. This is because an effect of easilyremoving the ink agglomerate on a surface of the ball is provided and,then, not only the blobbing of the written letter at the start ofwriting is suppressed but also an effect of enhancing the effect ofrealizing the soft smooth feeling of writing by a high volatile solventand quickly performing the transfer of the ink by addition of a chemicalsubstance represented by the chemical structure (1) or (2) when writingis executed under a high load is exerted.

Specific examples, the addition amount and the like of the mixture ofthe phosphoric acid ester and the amine-type compound are same as thosedescribed for in the embodiment (a).

According to this embodiment (b) of the present invention, beingdifferent from a prior method, the ink composition for the ballpoint pencapable of being excellent in suppressing the blobbing of the writtenletter at the start of writing, realizing the soft smooth feeling ofwriting and quickly performing the transfer of the ink when writing isexecuted under the high load can be provided.

In this embodiment (b) of the present invention, the reason for exertingsuch effects as described above is in the characteristics of the inkcomposition. Although it is uncertain as to the reason why the ink isexcellent in suppressing the blobbing at the start of writing, realizingthe soft smooth feeling of writing and quickly performing the transferof the ink when writing is executed under the high load can be obtained,it is due to using the chemical substance represented by the chemicalstructure (1) or (2) in an organic solvent-type ink, particularly, apigment-containing ink. This is considered as being that the chemicalsubstance represented by the chemical structure (1) or (2) which is hardto be present in an oil-based ink may control the solubility to the rawmaterial at the interface between the metallic ball and the ink. It isconsidered that, by such control, abrasion is reduced or an abrasioncoefficient is lowered and, then, a lubricating effect is executed.Under these circumstances, it has been possible to provide the oil-basedink composition for the ballpoint pen which improves the blobbing at thestart of writing and is excellent in realizing the soft smooth feelingof writing and quickly performing the transfer of the ink when writingis executed under the high load.

EMBODIMENT (c)

Another embodiment (c) of the present invention is characterized in thata solvent selected from among an alcohol, a polyhydric alcohol and aglycol ether each having no aromatic ring in the molecule as the mainsolvent occupies 50% by weight or more of an entire solvent, and the irkcomposition further comprises a phosphoric acid ester neutralizedmaterial as well as an additional solvent selected from among analcohol, a polyhydric alcohol and a glycol ether each having an aromaticring in an amount, based on an entire weight of the ink composition, offrom 0.1 to 15% by weight.

The ink composition for an oil-based ballpoint pen according to thisembodiment (c) comprises a phosphoric acid ester nuetralized material.According to the present invention, a coloring material, a resin andother ink components than the above-described components are containedin the ink composition; however, due to these components, the inkcomponents which are agglomerated on a surface of a ball tend to causethe blobbing of writing at the start of writing. Whereas, the phosphoricacid ester exerts an effect which facilitates removal of such inkagglomerate on the surface of the ball, Owing to this effect, there isan effect of suppressing the blobbing at the start of writing.

Details of specific examples of the phosphoric acid neutralizedmaterials or amounts thereof to be added can be same as those asdescribed in the above-described embodiment (a).

In this embodiment (c), by using an additional solvent selected fromamong the alcohol, the polyhydric alcohol and the glycol ether eachhaving an aromatic ring as an auxiliary solvent, simultaneously with thephosphoric acid ester neutralized material, in addition to the mainsolvent selected from among the alcohol, the polyhydric alcohol and theglycol ether each having no aromatic ring, an effect of action whichenhances an effect of peeling or repelling the ink from the surface of ametallic ball is exerted and, by this effect of action, it is possibleto suppress the blobbing of writing at the start of writing and enhancethe effect of realizing a soft smooth feeling of writing and such effectas described above is remarkable.

As for the alcohol, polyhydric alcohol and glycol ether each having thearomatic ring to be used in this embodiment (c), those described belowand the like can be mentioned.

As for the alcohols, benzyl alcohol, ethylene oxide derivatives thereofor propylene oxide derivatives, and derivatives of a mixture of EO andPO may be mentioned; as for the glycol ethers, ethylene glycolmonophenyl ether, ethylene oxide derivatives thereof or propylene oxidederivatives thereof, and derivatives of a mixture of EO and PO may bementioned and, further, propylene glycol monophenyl ether, ethyleneoxide derivatives thereof or propylene oxide derivatives thereof, andderivatives of a mixture of EO and PO may be mentioned and, stillfurther, butylene glycol monophenyl ether, ethylene oxide derivativesthereof or propylene oxide derivatives thereof, and derivatives of amixture of EO and PO may be mentioned.

The amount of the alcohol, polyhydric alcohols and glycol ether eachhaving an aromatic ring to be added may be, based on the irkcomposition, from 0.1 to 15% by weight and, preferably, from 0.5 to 10%by weight. When it is less than 0.1% by weight, an effect is diminished,while, when it is more than 15% by weight, a phenomenon occurs in whicha drawn line scribbled at a high speed is broken.

According to the embodiment (c) according to the present invention,being different from a prior method, the ballpoint pen capable of beingexcellent in suppressing the blobbing of the written letter at the startof writing and realizing the soft smooth feeling of writing can beprovided.

In this embodiment (c) of the present invention, the reason for exertingsuch effects as described above is in the characteristics of the inkcomposition, namely, the reason of obtaining the ink excellent insuppressing the blobbing of the written letter at the start of writingand the soft smooth feeling of writing is because the effect of thephosphoric acid ester neutralized material can be supported by using asmall amount of the solvent having the aromatic ring in analiphatic-based organic solvent-type ink. In other words, an effect ofsuppressing an irk leakage into the metallic ball can be exerted. By theeffect, it is possible to provide the oil-based ink composition for theballpoint pen which uses the main solvent as defined in the Claims,exerts a smooth feeling of writing based on the composition thereof,supplements the performance of the phosphoric acid ester neutralizedmaterial by adding a small amount of the solvent having an aromaticring, improves the blobbing at the start of writing and is excellent inrealizing the soft smooth feeling of writing.

<Other Components>

Further, in the oil-based ink composition for the ballpoint penaccording to the present invention, in any of the above-describedembodiments, if desired, a rust preventive, an antifungal, a surfactant,a lubricant, a wetting agent and the like, which are compatible withoutadversely affecting the ink, can further be compounded. In particular, afatty acid or the like can favorably be used as the lubricant. Also, anon-volatile solvent or the like compatible with the main solvent can becompounded as an additive for preventing drying, within the range of notcausing any adverse effect in view of the product properties.

<Ink Follower>

In a case of using the ink composition according to the presentinvention in a ballpoint pen, an ink follower is preferably imparted toa rear end of the ballpoint pen. Since the solvent used is volatile, theink follower is provided for preventing volatilization, moistureabsorption and ink leakage.

The ink follower must exhibit a low permeability and a low diffusionproperty to a solvent used for the ink and a base material thereof maybe a non-volatile or sparingly volatile fluid body, more specifically,non-silicon-base oils and fats fundamentally incompatible with thesolvent according to the present invention, particularly, the mainsolvent, such as polybutene and liquid paraffin, may be used, In a casein which such a substance as described above has a low viscosity, athickener or a gelling agent may be used. Specific examples thereofinclude metal soaps, bentonites, fatty acid amides, hydrogenated castoroils, metal fine particles including those of titanium oxide, silica,alumina or the like, celluloses, and elastomers.

EXAMPLES

The present invention is described in greater detail below withreference to Examples; however, the present invention is not limited tothese Examples.

Examples Related to Embodiment (a)

In regard to a phosphoric acid ester neutralized material to be used inthe preparation of ink, a phosphoric acid ester and an amine-typecompound were each dissolved in the main solvent to prepare respective2% solutions, Then, a neutralization titration was performed by usingthe thus-prepared solutions, to thereby obtain a neutralization point.By using the neutralization ratio obtained by this neutralizationtitration, the components were mixed at a predetermined value asdescribed below, to thereby obtain the phosphoric acid ester neutralizedmaterial.

Components used in Examples and Comparative Examples described below areas follows:

SPIRON Violet C-RH: a spirit-soluble dye in which methyl violet is abasic material;

SPIRON Yellow C-GNH: a spirit-soluble yellow dye;

Printex#35: carbon black;

HIRACK 110H: alcohol-soluble resin;

Chromophthal Blue A-3R: indathrene (pigment);

Chromophthal Violet B: dioxadine violet (pigment); and

YP90L: terpene phenol resin.

Examples 1 to 4 and Comparative Examples 1 to 4 are described below.

Example 1

Carbon black #25 [produced by Mitsubishi Chemical 10%  Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui 5% Chemical Co., Ltd.] YP90L[produced by Yasuhara Chemical K.K.] 8% Polypropylene glycol (averagemolecular weight: 5% 4000) Phosphoric acid ester: Prisurf A208B 1.47%  Amine-type compound: polyoxyethylene alkylamine 1.03%   (AMIET105)3-methoxybutanol 5% 3-methoxy, 3-methyl, 1-butanol 64.5%  

Example 2

SPIRON Violet C-RH [produced by Hodogaya Chemical 8% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5% Co., Ltd.]Printex#35[produced by Degussa AG] 8% Polyvinyl butyral BL-1 [producedby Sekisui 4% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12%  Ltd.] Polypropylene glycol (average molecular weight:3% 4000) Phosphoric acid ester: Phosphanol LB-400 1.46%   Amine-typecompound: polyoxyethylene oleylamine 1.04%   (TAMNO-5) 3-methoxybutanol5% 3-methoxy, 3-methyl, 1-butanol 52.5%  

Example 3

SPIRON Blue C-RH [produced by Hodogaya Chemical 8% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8% Polyvinyl butyral BL-1 [producedby Sekisui 4% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 8% Ltd.] Polypropylene glycol (average molecular weight:9% 2000) Phosphoric acid ester: Prisurf A208B 1.47%   Amine-typecompound: polyoxyethylene alkylamine 1.03%   (AMIET105) 3-methoxy,3-methyl, 1-butanol 56.5%  

Example 4

SPIRON Violet C-RH [produced by Hodogaya Chemical  10% Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy]  5% Polyvinyl butyralBL-S [produced by Sekisui  3% Chemical Co., Ltd.] HIRACK 110H [producedby Hitachi Chemical Co.,  12% Ltd.] Polypropylene glycol (averagemolecular weight:  9% 2000) Phosphoric acid ester: Phosphanol LB-4001.46%  Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5)3-methoxy, 3-methyl, 1-butanol 58.5% 

Comparative Example 1

Carbon black #25 [produced by Mitsubishi Chemical  10% Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui  5% Chemical Co., Ltd.]YP90L [produced by Yasuhara Chemical K.K.]  8% Phosphoric acid ester:Prisurf A208B 1.47%  Amine-type compound: polyoxyethylene alkylamine1.03%  (AMIET105) 3-methoxybutanol  5% 3-methoxy, 3-methyl, 1-butanol69.5% 

Comparative Example 2

SPIRON Violet C-RH [produced by Hodogaya Chemical 8% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5% Co., Ltd.]Printex#35[produced by Degussa AG] 8% Polyvinyl butyral BL-1 [producedby Sekisui 4% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12%  Ltd.] Phosphoric acid ester: Phosphanol LB-4001.46%   Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5) 3-methoxybutanol 5% 3-methoxy, 3-methyl, 1-butanol 55.5%  

Comparative Example 3

SPIRON Blue C-RH [produced by Hodogaya Chemical 8% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8% Polyvinyl butyral BL-1 [producedby Sekisui 4% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 8% Ltd.] Castor oil derivative 9% Phosphoric acid ester:Prisurf A208B 1.47%   Amine-type compound: polyoxyethylene alkylamine1.03%   (AMIETO 105) 3-methoxy, 3-methyl, 1-butanol 56.5%  

Comparative Example 4

SPIRON Violet C-RH [produced by Hodogaya Chemical  10% Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy]  5% Polyvinyl butyralBL-S [produced by Sekisui  3% Chemical Co., Ltd.] HIRACK 110H [producedby Hitachi Chemical Co.,  12% Ltd.] Polyethylene glycol (averagemolecular weight: 200)  9% Phosphoric acid ester: Phosphanol LB-4001.46%  Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5)3-methoxy, 3-methyl, 1-butanol 58.5% 

The inks obtained in Examples and Comparative Examples above were eachfilled in a ballpoint pen and subjected to evaluation tests as describedbelow.

The ballpoint pen used in the test had a polypropylene tube having aninside diameter of 1.60 mm and a stainless steel tip (the ball was madeof a superhard metal or a carbide metal and had a diameter of 1.0 mm).30 minutes after the filling, the evaluations were performed under thecondition of 25° C. and 65% RH as described below.

1) Evaluation of Blobbing at the Start of Writing (Sensory Evaluation):

Letters of

(Mitsubishi)” were written and, then, the evaluation was performed basedor an extent of the blobbing of the letters.

AA: almost no blobbing (the first or second line and the following linesof

(mitsu/three)” were able to be written);

BB: slight blobbing (the second line of

(mitsu/three)” was slightly blobbed but the following lines were able tobe written without blobbing);

CC: slightly heavy blobbing (no blobbing for

(bishi)”); and

DD: very heavy blobbing (writing of

(bishi)” was not possible to the last).

2) Evaluation of Blobbing at the Start of Writing (MechanicalEvaluation):

Under the condition of 25° C. and 65% RH, a pen was set at 60° and aload of 200 g was applied thereon, paper in contact with the pen wasmoved at a rate of 2 m/min and, then, a drawn line was evaluated. Atthat time, a distance of the drawn line from a start point was measured.Five pens were prepared and an average value of such measurements wasused as a measured value.

AA: Measured value≦10 mm;

BB: 10 mn<Measured value≦50 mm;

CC: 50<Measured value≦100 mm; and

DD: 100<Measured value.

3) Evaluation of Blobbing at the Start of Writing for a Short Period orTime (Sensory Evaluation)

The letters

(Mitsubishi)” were written and the evaluation was performed by theextent of the blobbing of the letters.

After the evaluation in 1), the same test was subsequently executed forperiods of from 1 to 60 minutes (1, 3, 5, 7, 10 and 20 minutes). At thattime, the test was continued without wiping the pen tip.

AA: almost no blobbing under all conditions (the first or second lineand the following lines of

(mitsu)” were able to be written);

BB: slight blobbing in a period of from 1 to 20 minutes (the second lineof

(mitsu)” was slightly blobbed but the following lines were able to bewritten without blobbing);

CC: comparatively heavy blobbing in a period of from 1 to 20 minutes (noblobbing for

(bishi)”); and

DD: Very heavy blobbing in a period of from 1 to 20 minutes (writing of

(bishi)” was not possible until the last). TABLE 1 Evaluation resultComparative Example Example 1 2 3 4 1 2 3 4 1) Evaluation AA AA AA AA CCCC CC CC 2) Evaluation AA AA AA AA DD DD DD DD 3) Evaluation AA AA AA AACC CC CC CC

As is apparent from the results shown above, it has been found that theink compositions of Examples 1 to 4 which are within the scope of thepresent invention are extremely favorable concerning the blobbing at thestart of writing and also in a soft smooth feeling of writing ascompared with the ink compositions of Comparative Examples 1 to 4 whichare out of the scope of the present invention.

Examples Related to Embodiment (b)

With regard to the phosphoric acid ester neutralized material to be usedin the preparation of ink, a phosphoric acid ester and an amine-typecompound were each dissolved in the main solvent to prepare respective2% solutions. Then, a neutralization titration was performed by usingthe thus-prepared solutions, to thereby obtain a neutralization point.By using the neutralization ratio obtained by this neutralizationtitration, components were mixed at a predetermined value as describedbelow, to thereby obtain the phosphoric acid ester neutralized material.Further, with regard to substances represented by the chemical structure(1) or (2) to be used in Examples, a 50% by weight solution thereof in amain solvent to be used was prepared and, then, the thus-preparedsolution was mixed with other components and used.

Components used in Examples and Comparative Examples to be describedbelow are as follows;

YP90L: terpene phenol resin;

SPIRON Violet C-RH: a spirit-soluble dye in which methyl violet is abasic material;

SPIRON Yellow C-GNH: a spirit-soluble yellow dye;

Printex#35: carbon black;

HIRACK 110H: alcohol-soluble resin;

SPIRON Blue C-RH: a spirit-soluble blue dye;

Chromophthal Blue A-3R: indathrene (pigment);

Chromophthal Violet B: dioxadine violet (pigment); and

POE (2) lauryl ether: polyoxyethylene 2-mol adduct lauryl ether.

Examples 11 to 14 and Comparative Examples 11 to 14 are described below.

Example 11

Carbon black #25 [produced by Mitsubishi Chemical 10.0%  Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui 5.0% Chemical Co., Ltd.]YP90L [produced by Yasuhara Chemical K.K.] 8.0% Stearyl dimethylaminoacetaic acid betaine (Bista- 2.0% MS) [produced by MatsumotoYushi-Seiyaku Co., Ltd.] 3-methoxy, 3-methyl, 1-butanol 2.0% Phosphoricacid ester: Prisurf A208B 1.47%  Amine-type compound: polyoxyethylenealkylamine 1.03%  (AMIET105) 3-methoxybutanol 5.0% 3-methoxy, 3-methyl,1-butanol 65.5% 

Example 12

SPIRON Violet C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5.0% Co., Ltd.]Printex#35[produced by Degussa AG] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12.0%  Ltd.] Alkyl (C14 to 18) dimethylamino acetic acidbetaine 1.0% (ANHITOL 86B) [produced by Kao Corporation] 3-methoxy,3-methyl, 1-butanol 1.0% Phospholic acid ester: phosphanal LB-400 1.46% Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5)3-methoxybutanol 5.0% 3-methoxy, 3-methyl, 1-butanol 53.5% 

Example 13

SPIRON Blue C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4.0% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] Lauryl dimethylamino acetic acidbetaine (ADEKA 2.5% AMPHOTE PB-30L [produced by Asahi Denka Co., Ltd.]HIRACK 110H [produced by Hitachi Chemical Co., 8.0% Ltd.] Phosphoricacid ester: Prisurf A208B 1.47%  Amine-type compound: polyoxyethylenealkylamine 1.03%  (AMIET105) 3-methoxy, 3-methyl, 1-butanol 63.0% 

Example 14

SPIRON Violet C-RH [produced by Hodogaya Chemical 10.0% Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy]  5.0% Polyvinyl butyralBL-S [produced by Sekisui  3.0% Chemical Co., Ltd.] Myristic acid amidepropyl betaine (BISTA-MAP)  1.0% [produced by Matsumoto Yushi-SeiyakuCo., Ltd.] HIRACK 110H [produced by Hitachi Chemical Co., 12.0% Ltd.]Phosphoric acid ester: Phosphanol LB-400 1.46% Amine-type compound:polyoxyethylene oleylamine 1.04% (TAMNO-5) 3-methoxy, 3-methyl,1-butanol 66.5%

Comparative Example 11

Carbon black #25 [produced by Mitsubishi Chemical 10.0% Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui  5.0% Chemical Co., Ltd.]YP90L [produced by Yasuhara Chemical K.K.]  8.0% Phosphoric acid ester:Prisurf A208B 1.47% Amine-type compound: polyoxyethylene alkylamine1.03% (AMIET105) 3-methoxybutanol  5.0% 3-methoxy, 3-methyl, 1-butanol69.5%

Comparative Example 12

SPIRON Violet C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5.0% Co., Ltd.]Printex#35[produced by Degussa AG] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12.0%  Ltd.] 3-methoxybutanol 5.0% 3-methoxy, 3-methyl,1-butanol 58.0% 

Comparative Example 13

SPIRON Blue C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4.0% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 8.0% Ltd.] POE (2) lauryl ether 1.5% Phosphoric acidester: Prisurf A208B 1.47%  Amine-type compound: polyoxyethylenealkylamine 1.03%  (AMIETO 105) 3-methoxy, 3-methyl, 1-butanol 64.0% 

Comparative Example 14

SPIRON Violet C-RH [produced by Hodogaya Chemical 10.0%  Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy] 5.0% Polyvinyl butyralBL-S [produced by Sekisui 3.0% Chemical Co., Ltd.] HIRACK 110H [producedby Hitachi Chemical Co., 12.0%  Ltd.] Castor oil derivative 2.5%Phosphoric acid ester; Phosphanol LB-400 1.46%  Amine-type compound:polyoxyethylene oleylamine 1.04%  (TAMNO-5) 3-methoxy, 3-methyl,1-butanol 65.0% 

The inks obtained in Examples and Comparative Examples were each filledand subjected to evaluation tests as described below.

The ballpoint pen used in the tests had a polypropylene tube having aninside diameter of 1.60 mm and a stainless steel tip (the ball was madeof a superhard metal or a carbide metal and had a diameter of 1.0 mm).30 minutes after the filling, the evaluations described below wereperformed under the condition of 25° C. and 65% RH.

1) Evaluation of blobbing at the start of writing (sensory evaluation):the same as in the embodiment (a). 2) Evaluation of blobbing at thestart of writing (mechanical evaluation): the same as in the embodiment(a).

The ballpoint pen used in the tests to be described below had apolypropylene tube having an inside diameter of 1.60 mm and a stainlesssteel tip (the ball was made of a superhard metal or a carbide metal andhad a diameter of 0.7 mm). 30 minutes after the filling, the evaluationsto be described below were performed under the condition of 25° C. and65% RH. In a writing performance under a high load, as the diameter ofthe ball is smaller, a writing pressure becomes larger and, therefore,the diameter of the ball was intentionally changed, in this test, to onesmaller than those in the tests in 1) and 2).

3) Evaluation of Writing Under a High Load

Under the condition of 25° C. and 65% RH, a pen was set at 60° and aload of 300 g was applied thereon, paper in contact with the pen wasmoved at a rate of 4.5 m/min in a rotating manner and, then, a drawnline was evaluated. At that time, a drawn line condition in which inkwas not transferred by means of the rotation of the ball was subjectedto a sensory evaluation. TABLE 2 Evaluation result Comparative ExampleExample 11 12 13 14 11 12 13 14 1) Evaluation AA AA AA AA CC DD CC CC 2)Evaluation AA AA AA AA DD DD DD DD 3) Evaluation aa aa aa aa dd dd dd ddaa: No problem at all;CC: A few portions in which ink was not transferred; anddd: Many portions in which ink was not transferred in an aggravatedstate.

As is apparent from the results shown above, it has been found that theink compositions of Examples 11 to 14 which are within the scope of thepresent invention are extremely favorable concerning blobbing at thestart of writing and are excellent in a soft smooth feeling of writingand in quickly performing the transfer of the ink at the time of writingin a low speed as compared with the ink compositions of ComparativeExamples 11 to 14 which are out of the scope of the present invention.

Examples Related to Embodiment (c)

In regard to the phosphoric acid ester neutralized material to be usedin the preparation of ink, a phosphoric acid ester and an amine-typecompound were each dissolved in the main solvent to prepare respective2% solutions. Then, a neutralization titration was performed by usingthe thus-prepared solutions, to thereby obtain a neutralization point.By using a neutralization ratio obtained by this neutralizationtitration, the components were mixed at a predetermined value, asdescribed below, to thereby obtain a phosphoric acid ester neutralizedmaterial.

Components used in Examples and Comparative Examples to be describedbelow are as follows:

YP90L: terpene phenol resin;

SPIRON Violet C-RH: a spirit-soluble dye in which methyl violet is abasic material;

SPIRON Yellow C-GNH; a spirit-soluble yellow dye;

Printex#35: carbon black;

HIRACK 110H: alcohol-soluble resin;

SPIRON Blue C-RH: a spirit-soluble blue dye;

Chromophthal Blue A-3R; indathrene (pigment); and

Chromophthal Violet B: dioxadine violet (pigment).

Examples 21 to 24 and Comparative Examples 21 to 24 are described below.

Example 21

Carbon black #25 [produced by Mitsubishi Chemical 10.0%  Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui 5.0% Chemical Co., Ltd.]YP90L [produced by Yasuhara Chemical K.K.] 8.0% Phosphoric acid ester:Prisurf A208B 1.47%  Amine-type compound: polyoxyethylene alkylamine1.03%  (AMIET105) 3-methoxybutanol 5.0% Benzyl alcohol 10.0%  3-methoxy,3-methyl, 1-butanol 62.5% 

Example 22

SPIRON Violet C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5.0% Co., Ltd.]Printex#35[produced by Degussa AG] 8.0% Polyvinyl butyral BL-l [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12.0%  Ltd.] Phosphoric acid ester: Phosphanol LB-4001.46%  Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5)3-methoxybutanol 5.0% Ethylene glycol monophenyl ether 7.0% 3-methoxy,3-methyl, 1-butanol 48.5% 

Example 23

SPIRON Blue C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4.0% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8.0% Polyvinyl butyral BL-l [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 8.0% Ltd.] Phosphoric acid ester: Prisurf A208B 1.47% Amine-type compound: polyoxyethylene alkylamine 1.03%  (AMIET105)Ethylene glycol monophenyl ether 5.0% 3-methoxy, 3-methyl, 1-butanol60.5% 

Example 24

SPIRON Violet C-RH [produced by Hodogaya Chemical 10.0%  Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy] 5.0% Polyvinyl butyralBL-S [produced by Sekisui 3.0% Chemical Co., Ltd.] HIRACK 110H [producedby Hitachi Chemical Co., 12.0%  Ltd.] Phosphoric acid ester: PhosphanolLB-400 1.46%  Amine-type compound: polyoxyethylene oleylamine 1.04% (TAMNO-5) Benzyl alcohol 10.0%  3-methoxy, 3-methyl, 1-butanol 55.5% 

Comparative Example 21

Carbon black #25 [produced by Mitsubishi Chemical 10.0% Co., Ltd.]Polyvinyl butyral BL-S [produced by Sekisui  5.0% Chemical Co., Ltd.]YP90L [produced by Yasuhara Chemical K.K.]  8.0% 3-methoxybutanol  5.0%Benzyl alcohol 10.0% 3-methoxy, 3-methyl, 1-butanol 65.0%

Comparative Example 22

SPIRON Violet C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONYellow C-GNH [produced by Hodogaya Chemical 5.0% Co., Ltd.]Printex#35[produced by Degussa AG] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 12.0%  Ltd.] Phosphoric acid ester: Phosphanol LB-4001.46%  Amine-type compound: polyoxyethylene oleylamine 1.04%  (TAMNO-5)3-methoxybutanol 5.0% 3-methoxy, 3-methyl, 1-butanol 55.5% 

Comparative Example 23

SPIRON Blue C-RH [produced by Hodogaya Chemical 8.0% Co., Ltd.] SPIRONViolet C-RH [produced by Hodogaya Chemical 4.0% Co., Ltd.] ChromophthalBlue A-3R [produced by Ciba Geigy] 8.0% Polyvinyl butyral BL-1 [producedby Sekisui 4.0% Chemical Co., Ltd.] HIRACK 110H [produced by HitachiChemical Co., 8.0% Ltd.] 3-methoxy, 3-methyl, 1-butanol 68.0% 

Comparative Example 24

SPIRON Violet C-RH [produced by Hodogaya Chemical 10.0%  Co., Ltd.]Chromophthal Violet B [produced by Ciba Geigy] 5.0% Polyvinyl butyralBL-S [produced by Sekisui 3.0% Chemical Co., Ltd.] HIRACK 110H [producedby Hitachi Chemical Co., 12.0%  Ltd.] Phosphoric acid ester: PhosphanolLB-400 1.46%  Amine-type compound: polyoxyethylene oleylamine 1.04% (TAMNO-5) Xylene 5.0% 3-methoxy, 3-methyl, 1-butanol 63.8% 

The inks obtained in Examples and Comparative Examples were each filledand subjected to evaluation tests as described below.

The ballpoint pen used in the tests had a polypropylene tube having aninside diameter of 1.60 mm and a-stainless steel tip (the ball was madeof a superhard metal or a carbide metal and had a diameter of 1.0 mm).30 minutes after the filling, the evaluations to be described below wereperformed under the condition of 25° C. 65%.

-   1) Evaluation of blobbing at the start of writing (sensory    evaluation): the same as in the embodiment (a).-   2) Evaluation of lobbing at the start of writing (mechanical    evaluation): the same as in the embodiment (a).-   3) Evaluation of blobbing at the start of writing (mechanical    evaluation):

Under the condition of 25° C. and 65% RH, a pen was set at 60° and aload of 200 g was applied thereon, paper in contact with the pen wasmoved at a rate of 2 m/min and, then, a drawn line was evaluated. Atthat time, the distance of the drawn line from a start point wasmeasured. Five pens were prepared and an average value of suchmeasurements was used as a measured value. Further in order to evaluatethe blobbing over a long period of time, a period of leaving was set at3 days. TABLE 3 Evaluation result Comparative Example Example 21 22 2324 21 22 23 24 1) Evaluation AA AA AA AA DD CC DD DD 2) Evaluation AA AAAA AA DD CC DD DD 3) Evaluation BB BB BB BB DD DD DD DDAA: Measured value ≦10 mm;BB: 10 mm < Measured value ≦50 mm;CC: 50 < Measured value ≦100 mm; andDD: 100 < Measured value.

As is apparent from the results shown above, it has been found that theink compositions of Examples 21 to 24, which are within the scope of thepresent invention, are extremely favorable concerning the blobbing atthe start of writing and are excellent in a soft smooth feeling ofwriting compared with the ink compositions of Comparative Examples 21 to24 which are out of the scope of the present invention.

INDUSTRIAL APPLICABILITY

According to the present invention, being different from a prior method,there is provided an ink composition for a ballpoint pen capable ofsuppressing blobbing of a written letter at the start of writing andbeing excellent in quickly performing a transfer of an ink at the timeof writing under a high load. Further, there is also provided an inkcomposition for the ballpoint pen capable of suppressing the blobbing ofa written letter at the start of writing for a short period of time or along period of time and being excellent in a soft smooth feeling whenwriting.

1. An oil-based ink composition for a ballpoint pen, comprising at leasta coloring material, a resin and a solvent selected from the groupconsisting of an alcohol, a polyhydric alcohol and a glycol ether eachhaving a vapor pressure of 0.001 mmHg or more at 25° C. as a mainsolvent which occupies 50% or more of an entire solvent and, further,satisfying at least one of the following (a) to (c) (a) furthercomprising a phosphoric acid ester neutralized material andpolypropylene glycol; (b) further comprising a chemical substancerepresented by the following chemical structure (1) or (2):

wherein R represents an alkyl group having from 10 to 30 carbon atoms;or

wherein R represents an alkyl group having from 10 to 30 carbon atoms;and (c) while a solvent selected as the main solvent from the groupconsisting of an alcohol, a polyhydric alcohol and a glycol ether eachhaving no aromatic ring in a molecular structure occupies 50% by weightor more of an entire solvent, further comprising a phosphoric acid esterneutralized mixture and, still further comprising an additional solventselected from the group consisting of an alcohol, a polyhydric alcoholand a glycol ether each having an aromatic ring in an amount, based onan entire weight of the ink composition, of from 0.1 to 15% by weight.2. The oil-based ink composition for a ballpoint pen, according to claim1, wherein the glycol ether is a solvent represented by the followingchemical structure (3):

wherein R¹, R² and R³ each independently represent H or CH₃.
 3. Theoil-based ink composition for a ballpoint pen, according to claim 1,wherein the glycol ether is at least one type selected from the groupconsisting of: propylene glycol monomethyl ether, 1,3-butanediol,3-methoxy-1-butanol and 3-methyl-3-methoxy-1-butanol.
 4. The oil-basedink composition for a ballpoint pen, according to claim 1, wherein themain solvent is contained in an amount, based on an entire solvent, of60% by weight or more.
 5. The oil-based ink composition for a ballpointpen, according to claim 1, wherein the main solvent is contained in anamount, based on an entire solvent, of 70% by weight or more.
 6. Theoil-based ink composition for a ballpoint pen, according to claim 1,wherein the phosphoric acid ester neutralized material is contained inan amount, based on an entire weight of the ink composition, of from0.01 to 15% by weight.
 7. The oil-based ink composition for a ballpointpen, according to claim 1, wherein the polypropylene glycol has amolecular weight of 1,000 or more and is added in an amount of 0.01% byweight to 10% by weight.
 8. The oil-based ink composition for aballpoint pen, according to claim 1, wherein the coloring material is apigment, or a pigment and a dye in combination.
 9. The oil-based inkcomposition for a ballpoint pen, according to claim 1, wherein an amountof the chemical substance represented by the chemical structure (1) or(2) to be added is, based on the ink composition, from 0.5% by weight to10% by weight.
 10. The oil-based ink composition for a ballpoint pen,according to claim 9, further comprising a mixture of a phosphoric acidester and an amine-type compound.
 11. An oil-based ink composition for aballpoint pen comprising at least a coloring material, a resin, aphosphoric acid ester neutralized material, and polypropylene glycol,and further comprising a solvent selected from the group consisting ofan alcohol, a polyhydric alcohol and a glycol ether each having a vaporpressure of 0.001 mmHg or more at 25° C. as a main solvent whichoccupies 50% or more of an entire solvent.
 12. An oil-based inkcomposition for a ballpoint pen comprising at least a coloring material,a resin, and a chemical substance represented by the following chemicalstructure (1) or (2), and further comprising a solvent selected from thegroup consisting of an alcohol, a polyhydric alcohol and a glycol ethereach having a vapor pressure of 0.001 mmHg or more at 25° C. as a mainsolvent which occupies 50% or more of an entire solvent:

wherein R represents an alkyl group having from 10 to 30 carbon atoms;or

wherein R represents an alkyl group having from 10 to 30 carbon atoms.13. An oil-based ink composition for a ballpoint pen comprising at leasta solvent selected from the group consisting of an alcohol, a polyhydricalcohol and a glycol ether each having a vapor pressure of 0.001 mmHg ormore at 25° C. and having no aromatic ring in a molecular structure as amain solvent which occupies 50% or more of an entire solvent and,further, a coloring material, a resin, a phosphoric acid esterneutralized mixture and, still further, an additional solvent selectedfrom the group consisting of an alcohol, a polyhydric alcohol and aglycol ether each having an aromatic ring in an amount, based on anentire weight of the ink composition, of from 0.1 to 15% by weight. 14.An oil-based ballpoint pen, containing an oil-based ink compositionaccording to claim 1 in a refill.
 15. The oil-based ballpoint penaccording to claim 14, further containing an ink follower in a rear ofthe ink in the refill.